For the CPU, if you can afford it/need the extra cores, go for the 3600, if not go for the 3100. Ignore the 3300x as you can overclock the 3100 to be the same speed/faster on the stock cooler. Everything else seems to be good parts, make sure they are in fully working order before buying and try to pay with PayPal if possible. If you are looking for GPU power now then go for the 1660 Super, but I would advise waiting and trying to get a used 2060 etc when prices drop.